NASA-Funded Study Helps Untangle Methane Mystery

Ethane is the most abundant non-methane hydrocarbon in Earth's remote atmosphere, and shares its major emission sources with methane. Because methane and ethane are emitted from fossil fuel sources with characteristic emission ratios, long-term ethane records were used to investigate quantitatively methane's slowing growth rate. The long-term decline of the global concentration of atmospheric ethane (blue line) has closely matched the long-term decline of the global growth rate of atmospheric methane (pink line). This association suggests that changes in fossil fuel use are responsible for a significant portion of methane's long-term decline. This data set represents the longest continuous record of global atmospheric ethane levels. Image credit: UC Irvine 

Atmospheric methane is 20 times more potent as a greenhouse gas than carbon dioxide, but is present in Earth's atmosphere at much lower levels. Because of its large potential impact on climate change, scientists closely monitor its levels. Global levels of methane increased for decades in the 20th century as a result of worldwide industrial and agricultural activity. Then, from the 1980s through 2005, they leveled off, leaving scientists scratching their heads for a cause. Now, a new NASA-funded study by a UC Irvine-led science team appears to have accounted for most of the dramatic tapering-off during this period.

In results published Aug. 23 in the journal Nature, the team led by UC Irvine chemistry professor Donald Blake reported that the observed leveling-off in atmospheric methane is largely a result of changes in fossil fuel use - specifically, reductions in fugitive emissions of natural gas that can occur during fossil fuel exploration. Fugitive emissions include venting and flaring, evaporative losses, and equipment leaks and failures, but exclude combustion of fuels. The study finds these measures probably account for up to 70 percent of the slowing growth in atmospheric methane levels observed at the end of the 20th century.

Blake and his team, including co-author Mads Sulbaek Andersen, formerly of UCI and now with NASA's Jet Propulsion Laboratory in Pasadena, Calif., used nearly three decades of air samples of methane and ethane collected at remote locations across the globe for their analysis. Ethane is the most abundant non-methane hydrocarbon in Earth's atmosphere, and shares its major emission sources with methane. Because methane and ethane are emitted from fossil fuel sources with characteristic emission ratios, the scientists were able to use their long-term ethane records to investigate quantitatively the slowing growth rate of atmospheric methane.

The scientists found that the long-term decline in the global concentration of atmospheric ethane has closely matched the long-term decline of the global growth rate of atmospheric methane. This association shows that reductions in fossil fuel sources are responsible for a significant portion of methane's long-term decline. Close scrutiny of their data shows that the major factor was most likely the trapping of natural gas for use as a fuel source, sharply reducing the common practice of skyward venting and flaring of the methane from oil fields. Methane is the main ingredient in natural gas.

"It used to just be burned off as a waste product," said UC Irvine research associate and co-author Isobel Simpson. "The reason this is important is because methane is a potent greenhouse gas, second in importance only to carbon dioxide. We can't make real progress on climate change without tackling carbon dioxide, but bringing methane under control would certainly help."

Many researchers have tried to determine what prompted the declining trend in methane growth during the late 20th century. Last summer, a pair of papers in the journal Nature offered different causes: less natural gas from oil fields in one case and changing fertilizer and water practices in rice paddies in the other. Blake said his group had confirmed - using comprehensive global measurements - that the former was probably the major cause.

While these studies appear to have answered one part of the riddle, levels have started to climb again since 2007, prompting additional questions for scientists in this ongoing field of research.

"This paper speaks to the importance of scientific insight that only can be gained from decades of meticulous, sustained data recording," said Sulbaek Andersen. "The extent of this long-term record is quite unique. It has required the continuous, systematic work of researchers and students over a time span of almost 30 years."

Other organizations participating in the study included the National Oceanic and Atmospheric Administration and the University of Colorado.

nasa.gov

Methane Making An Appearance In Pennsylvania Water Supplies

Mike and Nancy Leighton live in Leroy Township, Pa., where residents have been dealing with flammable gas puddles and tainted well water.

Mike and Nancy Leighton's problems began on May 19, just as Mike was settling in to watch the Preakness Stakes. A neighbor in Leroy Township, Pa., called Mike and told him to check the water well located just outside his front door.

"I said, 'I'll be down in 15 minutes.' I wanted to see the race," Leighton said. But as the horses were racing, Leighton's well was overflowing. Typically, there's between 80 to 100 feet of head space between the top of the well and its water supply. But when Leighton went outside, the water was bubbling over the top.

Down the road, Ted and Gale Franklin's water well had gone dry. When water started coming out later that week, the liquid was "black as coal," according to Gale.

Since then, both families have been dealing with methane-contaminated water supplies, as well as dozens of mysterious, flammable gas puddles bubbling up on their properties.

Pennsylvania's Department of Environmental Protection blames a nearby hydraulic fracturing, or fracking, operation. It says methane gas has leaked out of the well, which is operated by Chesapeake Energy, and into the Leightons' and Franklins' water supplies.

The danger goes beyond contaminated water. In a letter to both families detailing test results and preliminary findings, state regulators wrote that "there is a physical danger of fire or explosion due to the migration of natural gas water wells." Chesapeake has installed ventilation systems at the two water wells, but the letter warns, "it is not possible to completely eliminate the hazards of having natural gas in your water supply by simply venting your well."

Nancy Leighton said the letter made her "a little nervous," pointing out that both families heat their homes with wood stoves and plan to do so this winter, regardless of whether the gas leaks have gone away.

"What are we going to do? We don't have any other options," Gail Franklin says.

A Methane Gas Express Elevator

So how did this happen?

The whole thing gets a bit confusing, because over and over again, the drilling industry has said fracking hasn't been linked to water contamination. Yet, here's a case where the state says a nearby natural gas well is to blame.

Here's why they're both right.

To frack a well, drillers crack up shale rock with explosives, then flush gas out of the ground with millions of gallons of fluid. For a long time, the fear has been that the chemicals are shot deep underground, then they and the gas find a way to seep back up a mile through the rock and the water supply.

That hasn't been conclusively documented, but what has been proven is something much more basic, and closer to the surface. It's not the technique of fracking — it's the pipe the gas uses to go from point A to point B that can be a problem.

Penn State University geologist David Yoxtheimer has been studying this issue, which is called methane migration. He explained that when a well is leaky, it becomes a methane gas express elevator. "Gas wants to migrate up," he said. "It's lighter. It's less dense. It finds itself trapped in these shallower, more porous formations. And during the drilling process, you can go down through these shallow formations, and as you're drilling through, suddenly you've created a conduit for those gases to escape."

A shoddy cement job is usually what's to blame. Gas wells are lined by a series of steel pipes surrounded by cement. And if the cement pour is rushed or poorly done, methane is going to get out of the well and into the ground. That's what state regulators say happened in 2009 in the same northeast Pennsylvania county where the Leightons and Franklins are currently dealing with stray gas.

'We Want Things Fixed'

Pennsylvania's Department of Environmental Protection fined Chesapeake Energy $900,000 for contaminating 16 families' water supplies. The company disputed the state's conclusion, but agreed to the fine — the largest environmental penalty in Pennsylvania history.

Since then, Pennsylvania regulators put much tougher drilling standards in place, in order to minimize methane leaks.

They mandated higher-quality cement and pipes in gas wells, among other changes. Chesapeake spokesman Michael Kehs said the company has improved its standards. He says the problem affecting the Leightons and Franklins is an "isolated incident," adding, "in this particular case there was a unique problem with a particular piece of equipment that was highly unusual."

Chesapeake is paying for water filtration devices at both families' homes, and in a statement said the malfunction that created the leak "has been identified and corrected. The surface expressions of methane have dramatically abated and are almost gone."

But Mike Leighton, who still has bubbling puddles in his yard, said he's fed up. "The newspapers keep minimizing the damage here, but it's here," said Leighton, pointing out bubbling gas puddles on his property. "And people think we're radicals, but we're not. We're just upset about the condition of our property, and we want things fixed.

"I want my real estate back to where it was before," he says. "And right now, it ain't worth dirt."

Amy Emmert, a policy adviser with the American Petroleum Institute, maintains that the leaky wells are few and far between. "A typical natural gas well is constructed with 3 million pounds of steel and cement," she said.

Still, it only takes one small hole, or one faulty piece of equipment, or one weak chunk of cement, to create problems on the surface.

By Scott DETROW@npr.org

Michael Leighton of Bradford County, PA, gives StateImpact Pennsylvania a tour of the devices Chesapeake Energy has installed in his basement.   


Methane gas has been bubbling into Leighton's water well and onto his property since mid-May. Pennsylvania's Department of Environmental Protection has linked the stray gas to a nearby Chesapeake well. 

NASA Discovers Yet Another Terrifying Global Warming Feedback Loop

As if the melting methane-packed permafrost and shrinking Arctic ice sheets weren't enough, NASA scientists have gone and uncovered a brand new feedback loop that could hasten climate catastrophe. Climate feedback loops, to the uninitiated, are phenomena that worsen the warming effect when triggered—which further worsens said phenomena, and around we go.

The permafrost is probably the gnarliest: there's a truly stupendous amount of greenhouse gases trapped in the frozen tundras across Siberia, Alaska, Canada, etc. As the permafrost melts, it releases those gases into the atmosphere, which warms it up, and melts more permafrost. If warming keeps apace, permafrost could soon contribute 35% of worldwide greenhouse gas emissions. That's terrifying.

So is this: "Researchers have known for years that large amounts of methane are frozen in Arctic tundra soils and in marine sediments ... But now a multi-institutional study led by Eric Kort of NASA’s Jet Propulsion Laboratory has uncovered a surprising and potentially important new source of methane: the Arctic Ocean itself."

That emphasis is mine, and a correct reading of the quote will include a dramatic and cartoony 'duhn-duhn-duhn' sound effect registered immediately after. And believe you me, it's justified. NASA scientists say that when they flew research flights over areas in the Arctic Sea where the ice was breaking up, they encountered higher than usual levels of methane. They then set out trying to determine where it came from:

By comparing the locations of the enhanced methane levels with airborne measurements of carbon monoxide, water vapor, and ozone, the researchers from six institutions pinpointed a source: the ocean surface, in places where there were cracks and openings in the sea ice cover. The cracks were allowing methane in the top layers of the sea to escape into the atmosphere. The team did not detect enhanced methane levels over areas of solid ice.Kort noted that previous studies had detected high concentrations of methane in Arctic surface waters, but no one had predicted that this dissolved methane would find its way into the overlying atmosphere ... “It’s possible that as large areas of sea ice melt and expose more ocean water, methane production may increase, leading to larger methane emissions,” he said. “While the methane levels we detected weren’t particularly large, the potential source region, the Arctic Ocean, is vast."

In other words, cracks in sea ice are allowing methane trapped in surface ocean to escape into the atmosphere. More warming means more cracks, which means more methane (and remember methane is a much more potent heat-trapping gas than carbon), which means more cracks.Further investigation certainly must be done to uncover the true scope of this threat, but it certainly doesn't sound good

By Brian Merchant@treehugger

Arctic Ocean Releasing "Significant" Amounts of Methane

Areas of open sea freed from sea ice are exuding the potent greenhouse gas, according to new research, which is bad news for climate change.

The surface waters of the Arctic Ocean may be releasing "significant" amounts of methane into the atmosphere, researchers reported yesterday in the journal Nature Geoscience.

Scientists flying a specially equipped plane over the region detected high concentrations of the heat-trapping gas close to the ocean surface during research flights in 2009 and 2010.

During flights in the high Arctic, above 82 degrees north latitude, the research jet's instruments detected methane that seemed to be coming from the ocean surface below. The signal was strongest when the plane was flying at low altitudes, sometimes just 500 feet above the water.

"We were surprised to see these enhanced methane levels over the Arctic at low altitudes," said lead author Eric Kort, a postdoctoral fellow at the California Institute of Technology's Jet Propulsion Laboratory. "It was surprising to find that it was probably coming out of the sea."

The signal was strongest over areas where sea ice was cracked or broken up.

The study's authors didn't have enough data to estimate the total amount of methane coming from the Arctic Ocean in a day or a year. But they do have measurements of methane flux -- how much of the gas is emitted from a specific area in a specific time frame.

In the portion of the Arctic Ocean they monitored, the daily methane flux was 2 milligrams per square meter -- roughly on par with emissions from the eastern Siberian Arctic shelf.

"It's not a particularly large number if you compare it to a high-latitude wetland that's really going in the summer," Kort said.

But the size of the Arctic Ocean that may be emitting methane could make it a significant source of the heat-trapping gas. One key question for scientists, Kort said, is how shrinking Arctic sea ice will affect those emissions.

The new study is one of the first analyses based on data collected by a recently concluded research program, "HIPPO," that sought to track the movement of greenhouse gases through the atmosphere using a Gulfstream V jet outfitted with scientific instruments and sensors.

The aircraft flew five long-haul journeys between the Earth's poles, swooping from low to high altitude and back again to allow the scientists to sample the composition of different layers of the atmosphere (ClimateWire, Sept. 8, 2011).

By Lauren Morello and ClimateWire

Arctic Ocean Could Be Source of Greenhouse Gas

The Arctic Ocean could be a significant contributor of methane, a powerful greenhouse gas, scientists reported on Sunday.

Researchers carried out five flights in 2009 and 2010 to measure atmospheric methane in latitudes as high as 82 degrees north.

They found concentrations of the gas close to the ocean surface, especially in areas where sea ice had cracked or broken up.

The study, published in the journal Nature Geoscience, wonders if this is a disturbing new 

mechanism that could accelerate global warming.

"We suggest that the surface waters of the Arctic Ocean represent a potentially important source of methane, which could prove sensitive to changes in sea-ice cover," it says.

If so, the Arctic Ocean would add to several identified "positive feedbacks" in Earth's climate system which ramp up the greenhouse effect.

One such vicious circle is the release of methane from Siberian and North American permafrost.

The thawing soil releases methane that has been locked up for millions of years, which adds to global warming -- which in turns frees more methane, and so on.

But this is the first evidence that points to a methane contribution from the ocean, not the land, in Arctic latitudes.

Levels of methane in the atmosphere are relatively low, but the gas is 20 times more effective that carbon dioxide (CO2) at trapping solar heat.

Scientists have been struggling to understand the movements of the methane curve.

There was a rapid increase in levels due to post-World War II industrialisation, followed by a period of relative stability in the 1990s and more recently, by another rise.

The new paper, led by Eric Kort at the California Institute of Technology Caltech), says measurements of methane over some parts of the ocean were comparable to coastal eastern Siberia where there has been permafrost thaw.

Noting that around 10 million square kilometres (3.86 million square miles) of the Arctic Ocean are subject to summer melting of sea ice, "the emissions rate we encountered could present a source of global consequence," it says.

The source of the sea methane is unclear, it stresses.

The gas is unlikely to have been belched from sediment in the continental shelf as it was found at locations over the deep ocean. One idea is that it comes from microbes at the ocean surface.

 AFP